Deep-sea slack wire mooring system

ABSTRACT

Apparatus for use in slack line mooring systems, especially those having an &#39;&#39;&#39;&#39;N&#39;&#39;&#39;&#39; configuration, which is useful for mooring bodies floating in water of unknown depth and which includes an anchoring device adapted to descend to and rest on the floor of a body of water. A cable storage means is associated with the anchoring device for storing a length of cable and is adapted to pay out, upon deployment of the anchoring device, a length D of cable therefrom approximately equal to the vertical distance between the floor of the body of water on which the anchor is to rest and the surface of said water. Of fundamental importance to the apparatus is the provision of means, adapted to be preconditioned by the magnitude of said length D of cable paid out, for permitting said cable storage means to pay out an additional length X of cable so related to said length D that the &#39;&#39;&#39;&#39;Scope&#39;&#39;&#39;&#39; of the cable system as determined by the ratio of said lengths according to the formula (D + X/D) assumes a suitable value, whereby to permit said cable to assume a configuration, especially an N configuration, under slack cable conditions of such proportions as to minimize the possibility of damage thereto which might otherwise result from an excess or deficiency of slack in said cable.

United States Patent [191 Starkey DEEP-SEA SLACK WIRE MOORING SYSTEM [75] Inventor: Bertrand J. Starkey, Saanichton, B.

C., Canada [73] Assignee: Hermes Electronics Limited,

Dartmouth, Nova Scotia, Canada [22] Filed: Jan. 22, 1973 [21] Appl. No.: 325,634

[30] Foreign Application Priority Data July 4, 1972 Canada 146263 [52] US. Cl. 9/8 R, 114/206 R, [14/230 [51] Int. Cl B63b 21/52 [58] Field of Search 9/8 R; 114/206 A, 206 R, 114/230 [56] References Cited UNITED STATES PATENTS 612,109 10/1898 Hutchins 9/8 R 2,903,716 9/1959 Zasada 9/8 R Primary Examiner-Albert J. Makay Assistant Examiner-Donald W. Underwood Attorney, Agent, or FirmSpencer & Kaye scoPE-sL l D "T [4 June 25, 1974 5 7] ABSTRACT Apparatus for use in slack line mooring systems, especially those having an N configuration, which is useful for mooring bodies floating in water of unknown depth and which includes an anchoring device adapted to descend to and rest on the floor of a body of water. A cable storage means is associated with the anchoring device for storing a length of cable and is adapted to pay out, upon deployment of the anchoring device, a length D of cable therefrom approximately equal to the vertical distance between the floor of the body of water on which the anchor is to rest and the surface of said water. Of fundamental importance to the apparatus is the provision of means, adapted to be preconditioned by the magnitude of said length D of cable paid out, for permitting said cable storage means to pay out an additional length X of cable so related to said length D that the Scope of the cable system as determined by the ratio of said lengths according to the formula (D X/D) assumes a suitable value, whereby to permit said cable to assume a configuration, especially an N configuration, under slack cable conditions of such proportions as to minimize the possibility of damage thereto which might otherwise result from an excess or deficiency of slack in said cable.

10 Claims, 8 Drawing Figures PATENTEDJIJN25I974 I 3,818,524

SHEET 1 [1F 5 FLOAT FIGI PRIOR ART PATEmEnJunzslsm SHEET 3 BF 5 .ELQV

PATENTEDJUNZSIQH SHEET Q [If 5 FIGS PAT-ENTED JUNZ 5 I974 SHEET 5 OF 5 SCANNER 76 r sOL. 60 ANCHOR R.O. M. INPUT FLOAT 4 BO'I'TOMING TO OUTPUT REV. RELEASE SWITCH CONVERSION STORE CLAMP 70 so 8. I CABLE Q Q DRUM CABLE REV. V DIGITIZER COMPARATOR DRUM COUNTER LOCK CABLE E DRUM 62 LOCK SWITCH l f REVERSTNC n GEARBOX 96 ER 4 COUN'I 9 SHIFT LEvER 2 76 9 RE v.

\ SOL, SOLENOID 60 FOR CABLE BOTTOMING CLAMP & ELOAT SWITCH RELEASE I DEEP-SEA SLACK WI MOORIING SYSTEM BACKGROUND OF THE INVENTION This invention relates to apparatus for use in so called slack line mooring systems especially useful for mooring bodies, such as buoys and the like, which are floating on the surface of a body of water. The device is especially useful in deep sea conditions where the water depth is unknown.

Slack line deep-sea mooring systems are very suitable for many applications due to their inherent simplicity and relatively low cost. Their main weakness is in the difficulty, if not the impossibility, of achieving a predictably long mooring life in deep-sea conditions, independent of the variations of current and sea states within the assumed design limits.

As is well known in the art, the length of the cable extending between the anchorage on the sea bed and the floating body must exceed the vertical distance which exists therebetween under average conditions by a certain amount so as to allow for the effects of varying current and sea states on the mooring system without any danger of the floating object being pulled under the water surface or the mooring cable becoming over stressed and breaking. This additional length of cable, as those skilled in the art will readily verify, gives rise to difficulties which are related to the fact that the long slack mooring line under zero current conditions will either have its lower portion sinking to the bottom, in the case of negatively buoyant lines, or its upper portion floating on the surface, in the case of positively buoyant lines. The first case, the most probable in deep sea moorings, is particularly dangerous from the mooring life point of view, as the cable touching the bottom is exposed to chafing and tangling and this normally spells a premature end of life. In fact, the life expectancy of the mooring becomes a statistical problem, depending almost entirely on the local current, swell and wind conditions which, in turn, determine the behaviour of the slack mooring cable. The second case is also potentially dangerous due to the possibility of the line becoming tangled with surface objects e.g. boats.

One known attempt to solve the above problem in the case of negatively buoyant mooring cables involves attaching a float to the cable a selected distance from the anchor to support the slack cable above the ocean bottom thus achieving a cable configuration commonly known as a N" configuration. Essentially the same effeet can be achieved where positively buoyant cables are used by attaching a weight to the cable at an appropriate place so that the slack length of cable is held beneath the ocean surface. The main difficulty here, however, is that the bottom depth must be known in order to determine the required position of the float (or weight as the case may be) along the cable. Secondly, the float (or weight) must be attached to the cable at this position. It will be appreciated that neither of these conditions can be met directly in automatically deployable buoys for application in any water depth, especially where water depth is, in the main, unknown.

SUMMARY OF THE INVENTION It is accordingly the main object of the present invention to provide apparatus for use in slack line, N configuration, mooring systems which is capable of deploying automatically, in water of unknown depth, a length of mooring cable sufticient to satisfy design requirements but insufficient to create problems of chafing, tangling etc. as referred to above.

Accordingly the invention provides, in one aspect, apparatus for use in slack line mooring systems, especially those having an N configuration, which is useful for mooring bodies floating in water of unknown depth and which includes an anchoring device adapted to descend to and rest on the floor of a body of water. A cable storage means is associated with the anchoring device for storing a length of cable and is adapted to pay out, upon deployment of the anchoring device, a length D of cable therefrom approximately equal to the vertical distance between the floor of the body of water on which the anchor is to rest and the surface of said water. Of fundamental importance to the apparatus is the provision of means, adapted to be preconditioned by the magnitude of said length D of cable paid out, for permitting said cable storage means to pay out an additional length X of cable so related to said length D that the Scope of the cable system as determined by the ratio of said lengths according to the formula (D X/D) assumes a suitable value, whereby to permit said cable to assume a configuration, especially an N configuration, under slack cable conditions of such proportions as to minimize the possibility of damage thereto which might otherwise result from an excess or deficiency of slack in said cable.

The numerical value of the Scope of the cable system as given by the ratio D X/D is preselected as a design parameter depending on various physical requirements. In many systems its value is about 1.3; however, the present invention is not to be limited to such value but is applicable to systems of any Scope suitable for the mooring system under consideration.

BRIEF DESCRIPTION OF THE VIEWS OF DRAWINGS FIGS. 5 and 6 are cut away perspective views of portions of the structure shown in FIG. 4;

FIG. 7 is a diagrammatic view of an electronic system for controlling the operation of the device of FIG. 4;

FIG. 8 is a diagrammatic view of a different form of control system for controlling the operation of the device of FIG. 4.

DETAILED DESCRIPTION FIG. 1 shows one form of a typical prior art N" configuration slack line mooring system wherein a float is attached to the correct length of mooring line a preselected distance from the anchor to hold the negatively buoyant cable above the sea bottom. This arrangement is only useful in situations where the water depth is accurately known and hence is of limited use because it is not possible, even where the sea bed has been fairly accurately charted, to take into account localized variations in the elevation of the sea bed such as are caused by troughs, ridges etc. therein.

The overall structure and operation of a mooring system incorporating the present invention will be apparent from FIGS. 2 and 3. The system shown incorporates a negatively buoyant cable but generally the same principles apply in the case of positively buoyant lines. The system shown includes a suitable anchor 18 adapted to descend, upon deployment, to the sea bed. As the anchor l8 descends, cable 12, which moors a surface buoy 14, is paid out from a storage drum 16 mounted within the anchor. A float 18 of buoyancy sufficient to support, in water, a length of cable 12 somewhat greater than the maximum expected sea depth is attached to the anchor 10 by means of a quick release device. Another device is provided to clamp the float 18 to cable 12 when an appropriate command is issued.

Before proceeding with a more detailed description of the device a brief account of the operation of the system will be given.

The deployment sequence is as follows. The buoyanchor package is dropped into the water. The anchor 10 separates from buoy l4 and descends, thus causing the storage drum 16 to pay out cable 12. A counter within the anchor counts the drum revolutions and thus establishes a predetermined relationship between the count and the ultimate anchor depth D. When the anchor l strikes the sea bottom the float 18 is automatically attached to cable 12 and its connection to the anchor released. The buoyancy of float 18 causes more cable to be unwound from the drum 16 within the anchor. At the time the anchor It) strikes the sea bottom, a new relationship is established between the length count then existing and the additional count created by the additional cable unwound by the float 18. The count existing at the time the anchor strikes bottom corresponds to the paid out length D of cable at that time. This length of cable, for purposes of this specification, will be taken to be equal to the water depth at the point where the anchor has come to rest and hence the same symbol D will be used for both dimensions. It is appreciated that these two dimensions in practice are not exactly equal to one another but the differences between them are considered to be so small in proportion to the magnitude of length D as to be negligible. The additional count caused by the action of the float 18 will, with reference to FIG. 3, correspond to an additional cable length X D a' where d is the minimum depth at which it is desired to stop the float. When this count corresponding to the additional length X is reached, the cable drum 16 is automatically locked and the mooring sequence is complete. The cable system as seen in FIG. 3 under slack line conditions has what is known in the art as an N configuration.

As can readily be deduced from FIG. 2, the length of cable to be supported by the float 18 is approximately:

Dd/2+Dd= 1.5 D- 1.5d

Reference has been made earlier to the scope of the cable system. For a given scope S the additional length of cable to be released may be given as X=(S 1 D For a complete understanding of the apparatus employed to carry out the above functions reference is now had to FIGS. 4-8.

The assembled buoy-anchor package, prior to deployment, is shown in FIG. 4. The spherical buoy 14 is temporarily connected to anchor 10 via any suitable releasable arrangement. The one shown in FIG. 4 includes a flexible band 20 encircling the buoy just above its plane of greatest diameter. Three rods 22 are each connected at one end to anchor 10 and at their opposing ends are engaged beneath band 20. Upon deployment of the system, tension applied to release cord 24 acts to pull out a release pin 26 which secures the band 20 about the buoy thus permitting the band 20 to open out and release rods 22. The buoy 14 and anchor 10 quickly separate with the latter, by virtue of its weight, quickly descending to the bottom.

The anchor 10 is of any suitable outside shape, and is of sufficient weight as to provide a firm anchorage for the buoy. It may be equipped with flukes etc. (not shown) to increase its holding ability on the sea bottom. Anchor 10 has an open or hollow interior for containing the various system components. The cable drum 16, upon which is wound a sufficient length of cable 12, is rotatably journalled in bearings 30, the latter being mounted in rigid supports 32 extending inwardly from the wall of the anchor body. The upper end of anchor 10 includes a hollow neck portion 34 adapted to receive float 18 therein.

The float I8 is of buoyancy sufficient to support the length of cable called for by formula (1); that is, the float 18 maintains the additional cable length X sufficiently taut as to maintain the N configuration. The float itself has a passageway 36 extending axially therethrough and through which cable 12 extends as it passes between the cable drum l6 and the buoy 14. Float 18 includes a stem portion 38 which contains a cavity 40 therein including a frustro-conical surface 42 defining the upper portion of said cavity. Mounted within cavity 40 are a plurality of segmented jaws 44 the upper ends of which are shaped to complement the frustro-conical surface 42. These jaws surround the cable 12 passing through the stem of the float. A compression spring 48 interposed between shoulders 50 on the stem and the base portions of the jaw segments 44 continually applies an upward thrust to the latter. If the jaws 44 are permitted to move upwardly under the influence of spring 48 the frustro-conical surfaces 42 cause the jaws 44 to close around the cable 12 and engage same whereby the float 18 is effectively clamped thereto.

In order to keep the jaws 44 in the relaxed condition and to permit free pay out of cable 12 through the float body, a lock pin 52 is mounted in the anchor neck and extends radially inwardly through an aperture 54 in the float stem and into an aperture provided in one of the segment jaws 44. Lock pin 52 serves a dual function in that it maintains the jaws 44 in the relaxed condition and also locks the float 18 to the anchor 10. A tension spring 54 is connected to the outer end of pin 52 and is sufficiently strong as to effect withdrawal of pin 52 to release jaws 44 as well as free the float 18 from the anchor. A pivoting latch 56 bears against a collar 58 on pin 52 thus preventing unwanted release of pin 52. Latch S6, in turn, is held in position by the plunger of solenoid 60 mounted in the neck of the anchor.

In order to stop rotation of cable drum 16, a drum locking solenoid 62 is rigidly affixed to the interior of anchor 14) by a suitable bracket adjacent to one end of drum 16. Upon command, the plunger 64 of the solenoid extends and comes into engagement with one of a plurality of lugs 66 welded to the drum flange thus locking drum 16 against further rotation.

A drum revolution counter 70 is also mounted adjacent to one end of the drum. Counter 70 includes a toothed wheel 72 which engages with a pin 74 affixed to the drum flange. Thus as the drum 16 rotates the counter is able to furnish an indication of the length of cable paid out therefrom.

Mounted on the interior of anchor adjacent the base of same is an inertia switch 76 capable of sensing the impact created by the anchor 10 striking the sea bottom. The function of this switch will be explained in greater detail later on. Also mounted on the anchor interior is a waterproof compartment for containing the electrical or mechanical control system for the device as will now be described.

The control system may be completely electrical in nature or it may comprise an electrical/mechanical device. The former will be described first with reference to FIG. 7.

The various components shown in FIG. 7 are all well known, per se, and hence a detailed description of each is not necessary. In this description, it is assumed that the apparatus has been deployed and that the anchor 10 is descending thus unwinding cable 12 from the drum 16. From FIG. 7 it is seen that the cable drum revolution counter 70 is connected to a digitizer 80, the latter converting the drum revolutions into electrical pulses which in turn are fed into a first input of an electronic comparator 82. The revolution counter 70 is also connected to an electronic scanner" 84 which feeds electrical pulses into a read-only memory matrix 86 thus building up on the input side of same an input value corresponding to the length of cable 12 paid out from the drum. When the anchor 10 hits the bottom the inertia switch 76 deactivates scanner 84 and powers solenoid 60 thus causing jaws 44 to clamp the float 18 to the cable and to release the float from the anchor. At the same time the inertia switch signals the memory matrix to convert the last cable length measurement (i.e. cable length D) to a length-to-be released" value D X such that the desired Scope or (D X/D) value is obtained. The memory matrix thus functions in the manner of a conversion table; for any value of D which has been applied thereto in theform of electronic pulses, it is capable of converting and providing at its output a value D X such that the ratio (D+ X/D) has a desired value. This (D X) value is applied to the second input of the comparator.

The float 18 has sufficient buoyancy that as soon as it is released from the anchor it starts to pull more cable from the drum 16. Thus the digitizer 80, which has already fed electrical pulses to the comparator of total value corresponding to the length D previously unwound from the drum, feeds more pulses thereto in accordance with the additional length of cable being unwound. When the total number of pulses from the digitizer 80 equals the value of length D X previously applied to the second input of the comparator, the latter senses the balance and emits a signal to the drum lock solenoid 62 thus locking the drum 16 against further rotation and completing the mooring sequence. Hence the additional length X of cable fed from drum 16 after the anchor reaches the bottom is sufficient to satisfy the particular ratio (D X/D) selected for the particular mooring system under consideration. 9

An alternative form of mechanical/electrical control system is shown in FIG. 8. In this arrangement the cable drum 16 is linked to a counter a via a reversible gear box 90. Gear box 90 is so arranged that when the anchor is descending to the bottom, the winch drum drives the counter in a 1:1 gear ratio so that by the time the anchor reaches the bottom the counter will have accummulated a value corresponding to the length D of cable unwound. However, when the anchor strikes bottom, the bottoming switch 76 emits an electrical signal which, as in the system of FIG. 7, activates solenoid 60 to release the float and clamp the cable thereto, and also activates reversing solenoid 92 which, in turn, moves shift arm 94 thereby effecting a gear change in gear box 90 such that the counter 70a is driven in the opposite direction as soon as the drum 16 begins to pay out the additional length X of cable. The gear ratio in the reverse direction is a function of the desired scope S of the system and is such that for each turn of the cable drum 16 the counter is turned in the opposite direction about l/S 1) turns. Hence, the counter 70a begins to subtract from the count corresponding to the length D unwound from the drum. When the drum 16 has rotated about (S 1) times the number of turns necessary to produce the initial count for lengthD the equation X (S 1) D is satisfied and'the counter has been driven back to the zero point. Further rotation of drum 16 causes the entire body of counter 70a to rotate whereby a pin 96 on the counter engages switch 98, which in turn activates the cable drum lock solenoid 62 thus preventing further rotation of the drum 16 in the manner described previously. Thus the additional length of cable X necessary to satisfy the pre-selected ratio (D X/D) has been paid out from drum 16.

In both the electronic system of FIG. 7 and the electromechanical system of FIG. 8 the number of turns of cable drum 16 has been taken to represent the length of cable let off therefrom. For purposes of convenience in describing the invention it has been assumed that a straight line relationship exists between these two values. However, in actual fact, this is not strictly accurate as the effective diameter of the wound up cable on the drum 16 progressively decreases as cable is let-off from same. Hence the number of turns of the drum does not indicate the exact length of cable paid off therefrom. Errors arising from this source may or may not pose a problem depending upon the range of depths over which the system is designed to operate. In any event,

the problem can easily be rectified. In the electronic system of FIG. 7 the read-only memory matrix can be programmed to apply a correcting factor to its output D X which takes into account the decreasing effective diameter of the cable drum. In the mechanical system arrangements can be made to count actual cable lengths instead of drum revolutions. The cable can be made to run in contact with a small pulley as it is paid out from the cable drum, such pulley being linked by reduction gears to the gear box 90 so that the exact length of cable paid out is counted by counter 70a.

Various modifications will occur to those skilled in the art. For example, a positively buoyant moving cable could be used. In this case, a weight (in place of the float) is attached to the cable when the anchor reaches the bottom, to keep the upper portion of the cable taut. The remaining portion of the cable, released according to the programming arrangement, will float, giving rise automatically to the desired cable shape preventing tangling. In still another version the counters can be replaced by properly calibrated pressure sensors.

1 claim:

l. Apparatus for use in slack line, N configuration, mooring systems especially useful for mooring bodies floating in water of unknown depth comprising: an anchoring means adapted to descend to and rest on the floor of a body of water, cable storage means associated with said anchoring means for storing a length of cable and adapted to pay out, upon deployment of the anchoring means, a length D of cable therefrom at least equal to the vertical distance between the floor of the body of water on which the anchoring means is to rest and the surface of said water, means, adapted to be preconditioned by the magnitude of the length D of cable paid out, for permitting said cable storage means to pay out an additional length X of cable so related to said length D that the Scope of the cable system as determined by the ratio of said lengths according to the formula (D X/D) assumes a selected value whereby to permit said cable to assume an N configuration under slack cable conditions of such proportions as to minimize the possibility of damage thereto which might otherwise result from an excess or deficiency of slack in said cable, a device for maintaining one of said lengths D and X of cable sufiiciently taut to provide said N configuration, and attaching means associated with the means for permitting pay out of said additional length of cable for attaching said device to said cable at a point therealong intermediate said lengths D and X of cable.

2. Apparatus according to claim 1 wherein the device for maintaining one of said lengths taut comprises a body whose buoyancy in water is opposite in sign to the sign of the buoyancy of said cable, said cable and body together having positive buoyancy so as to exert in water sufficient upward force to effect pay out of said additional length X of cable from said cable storage means.

3. Apparatus according to claim 1 further including means sensitive to said anchoring means reaching the floor of the body of water, said sensitive means being operatively connected with said means for permitting pay out of said additional length of cable X to initiate pay out of the latter when the anchoring means reaches the floor of the body of water.

4. Apparatus according to claim 2 including means sensitive to said anchoring means reaching the floor of the body of water, said sensitive means being operatively associated with said means for pennitting pay out of said additional length of cable X and also with said attaching means for initiating said pay out of said length X of cable and effecting attachment of said de vice to said cable when the anchoring means reaches the floor of said body of water.

5. Apparatus according to claim 2 including means sensitive to said anchoring means reaching the floor of said body of water, and releasable connecting means for attaching said body for maintaining one of said lengths D and X of said cable taut to said anchoring means, and means effecting an operative connection between said sensitive means and said releasable connecting means, to effect release of said last mentioned body from said anchoring means when the latter reaches the floor of the body of water.

6. Apparatus for use in slack line mooring systems especially useful for mooring bodies floating in water of unknown depth comprising: an anchoring means adapted to descend to and rest on the floor of a body of water, cable storage means associated with said anchoring means for storing a length of cable and adapted to pay out, upon deployment of the anchoring means, a length D of cable therefrom at least equal to the vertical distance between the floor of the body of water on which the anchoring means is to rest and the surface of said water, means, adapted to be preconditioned by the magnitude of the length D of cable paid out, for permitting said cable storage means to pay out an additional length X of cable so related to said length D that the Scope of the cable system as determined by the ratio of said lengths according to the formula (D X /D) assumes a selected value whereby to permit said cable to assume a configuration under slack cable conditions of such a character as to minimize the possibility of damage thereto which might otherwise result from an excess or deficiency of slack in said cable, a device for maintaining one of said lengths D and X of cable sufficiently taut to provide said configuration, and attaching means associated with the means for permitting pay out of said additional length of cable for attaching said device to said cable at a point therealong intermediate said lengths D and X of cable,

7. Apparatus according to claim 6 wherein the device for maintaining one of said lengths taut comprises a body whose buoyancy in water is opposite in sign to the sign of the buoyancy of said cable, said cable and body together having positive buoyancy so as to exert in water sufficient upward force to efi'ect pay out of said additional length X of cable from said cable storage means.

8. Apparatus according to claim 7 further including means sensitive to said anchoring means reaching the floor of the body of water, said sensitive means being operatively connected with said means for permitting pay out of said additional length of cable X to initiate pay out of the latter when the anchoring means reaches the floor of the body of water.

9. Apparatus according to claim 6 including means sensitive to said anchoring means reaching the floor of the body of water, said sensitive means being operatively associated with said means for permitting pay out of said additional length of cable X and also with said attaching means for initiating said pay out of said length X of cable and effecting attachment of said device to said cable when the anchoring means reaches the floor of said body of water.

10. Apparatus according to claim 7 including means sensitive to said anchoring means reaching the floor of said body of water, and releasable connecting means for attaching said body for maintaining one of said lengths D and X of said cable taut to said anchoring means, and means effecting an operative connection between said sensitive means and said releasable connecting means, to effect release of said last mentioned body from said anchoring means when the latter reaches the floor of the body of water.

a a at 

1. Apparatus for use in slack line, N configuration, mooring systems especially useful for mooring bodies floating in water of unknown depth comprising: an anchoring means adapted to descend to and rest on the floor of a body of water, cable storage means associated with said anchoring means for storing a length of cable and adapted to pay out, upon deployment of the anchoring means, a length D of cable therefrom at least equal to the vertical distance between the floor of the body of water on which the anchoring means is to rest and the surface of said water, means, adapted to be preconditioned by the magnitude of the length D of cable paid out, for permitting said cable storage means to pay out an additional length X of cable so related to said length D that the Scope of the cable syStem as determined by the ratio of said lengths according to the formula (D + X/D) assumes a selected value whereby to permit said cable to assume an N configuration under slack cable conditions of such proportions as to minimize the possibility of damage thereto which might otherwise result from an excess or deficiency of slack in said cable, a device for maintaining one of said lengths D and X of cable sufficiently taut to provide said N configuration, and attaching means associated with the means for permitting pay out of said additional length of cable for attaching said device to said cable at a point therealong intermediate said lengths D and X of cable.
 2. Apparatus according to claim 1 wherein the device for maintaining one of said lengths taut comprises a body whose buoyancy in water is opposite in sign to the sign of the buoyancy of said cable, said cable and body together having positive buoyancy so as to exert in water sufficient upward force to effect pay out of said additional length X of cable from said cable storage means.
 3. Apparatus according to claim 1 further including means sensitive to said anchoring means reaching the floor of the body of water, said sensitive means being operatively connected with said means for permitting pay out of said additional length of cable X to initiate pay out of the latter when the anchoring means reaches the floor of the body of water.
 4. Apparatus according to claim 2 including means sensitive to said anchoring means reaching the floor of the body of water, said sensitive means being operatively associated with said means for permitting pay out of said additional length of cable X and also with said attaching means for initiating said pay out of said length X of cable and effecting attachment of said device to said cable when the anchoring means reaches the floor of said body of water.
 5. Apparatus according to claim 2 including means sensitive to said anchoring means reaching the floor of said body of water, and releasable connecting means for attaching said body for maintaining one of said lengths D and X of said cable taut to said anchoring means, and means effecting an operative connection between said sensitive means and said releasable connecting means, to effect release of said last mentioned body from said anchoring means when the latter reaches the floor of the body of water.
 6. Apparatus for use in slack line mooring systems especially useful for mooring bodies floating in water of unknown depth comprising: an anchoring means adapted to descend to and rest on the floor of a body of water, cable storage means associated with said anchoring means for storing a length of cable and adapted to pay out, upon deployment of the anchoring means, a length D of cable therefrom at least equal to the vertical distance between the floor of the body of water on which the anchoring means is to rest and the surface of said water, means, adapted to be preconditioned by the magnitude of the length D of cable paid out, for permitting said cable storage means to pay out an additional length X of cable so related to said length D that the Scope of the cable system as determined by the ratio of said lengths according to the formula (D + X/D) assumes a selected value whereby to permit said cable to assume a configuration under slack cable conditions of such a character as to minimize the possibility of damage thereto which might otherwise result from an excess or deficiency of slack in said cable, a device for maintaining one of said lengths D and X of cable sufficiently taut to provide said configuration, and attaching means associated with the means for permitting pay out of said additional length of cable for attaching said device to said cable at a point therealong intermediate said lengths D and X of cable.
 7. Apparatus according to claim 6 wherein the device for maintaining one of said lengths taut comprises a body whose buoyancy in water is opposite in sign to the sign of the buoyancy of said cable, said cable and body together having positive buoyancy so as to exert in water sufficient upward force to effect pay out of said additional length X of cable from said cable storage means.
 8. Apparatus according to claim 7 further including means sensitive to said anchoring means reaching the floor of the body of water, said sensitive means being operatively connected with said means for permitting pay out of said additional length of cable X to initiate pay out of the latter when the anchoring means reaches the floor of the body of water.
 9. Apparatus according to claim 6 including means sensitive to said anchoring means reaching the floor of the body of water, said sensitive means being operatively associated with said means for permitting pay out of said additional length of cable X and also with said attaching means for initiating said pay out of said length X of cable and effecting attachment of said device to said cable when the anchoring means reaches the floor of said body of water.
 10. Apparatus according to claim 7 including means sensitive to said anchoring means reaching the floor of said body of water, and releasable connecting means for attaching said body for maintaining one of said lengths D and X of said cable taut to said anchoring means, and means effecting an operative connection between said sensitive means and said releasable connecting means, to effect release of said last mentioned body from said anchoring means when the latter reaches the floor of the body of water. 